Human and jellyfish combined to make the first living laser

Medical researchers from Harvard University have created the first "living laser"; a biological cell that's been
genetically engineered to produce a visible laser
beam.

Lasers need
two things to generate beams. They need a gain medium that
amplifies light, and an arrangement of mirrors to concentrate and
align that light.

Normal lasers, ever since their invention in the 1950s, use
synthetic gain materials like gases, crystals and dyes to amplify
photon pulses. But professor Seok-Hyun Yun and colleague Malte
Gather, instead used green fluorescent protein (GFP), which is used
to make jellyfish bioluminescent, as their gain material.

The team genetically engineered human embryonic kidney cells to produce GFP. They then placed a single cell between two mirrors. In terms of sizes:
the mirrors were spaced 20 micrometres apart (20 millionths of a
metre), and the cell was just 15 to 20 micrometres.

When the team ran pulses of blue light through the
kidney/jellyfish combo, a visible laser beam shot out. It only
lasted for a few nanoseconds, but the light could be easily
detected and carried useful information on the properties of the
cell. The cell also left the experiment unharmed.

Yun and Gather also noticed that the cell's natural
spherical shape acted like a lens, refocusing the light to induce
laser emissions at lower energy levels than needed in traditional
lasers with synthetic gain materials.

The technique has important applications in scientific and
medical fields. Biologists can turn cells into lasers to better
study their properties and makeup.

There's also the possibility, albeit one that's a long way off,
that doctors could one day make laser beams inside a patient's
body, to lase hazardous or cancerous tissue from deep inside the body, rather than firing
a laser from outside the skin.